Torque wrench for implantable medical devices

ABSTRACT

A torque wrench for implantable medical devices is disclosed. The torque wrench comprises a first and a second component. The first component has first and second ends with a bore extending between the first and second ends of the first component. The first component includes a plurality of anti-rotation members extending from an inner surface of the bore at the second end of the first component. A second component includes a middle portion having a first and second ends. A drive shaft extends from the first end and a plurality of fingers extends from an exterior surface of the second end. The second component is received in the bore of the first component such that the fingers are interdigitate with the anti-rotation members.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/174,455, filed on Apr. 30, 2009. The disclosure of the aboveapplication is incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates generally to wrenches, and, moreparticularly, to torque wrenches used to rotate a connector in animplantable medical device.

BACKGROUND

Many implantable medical devices such as pacemakers, defibrillators andneural stimulators can sense various physiological parameters throughmedical leads and/or deliver therapy to tissue. Leads include anelongated flexible lead body. The lead body comprises one or moreinsulated elongated conductors with one or more electrodes disposed at adistal end of the conductors.

To ensure the lead is properly secured to an implantable medical device,the proximal end of the conductor, referred to as a terminal pin, ispassed through a conductor bore in the connector block of a header. Asetscrew, which passes through a threaded setscrew bore that intersectswith the lead bore, is positioned to contact the conductor. A very smallsurgical torque wrench is then used to apply a certain amount of torqueto the setscrew. Torque applied to the setscrew should provide aretention force between the setscrew and the conductor that issufficiently large to prevent the conductor from dislodging from theheader yet low enough to prevent the torque from damaging the setscrewor conductor. After the setscrew has been tightened, the torque wrenchis typically discarded to ensure contaminants from one surgicalprocedure are not transferred to another procedure. It is desirable todevelop surgical torque wrenches that apply appropriate torque to asetscrew when securing a lead to a header and that are also inexpensivein order to reduce the cost of such procedures to patients.

BRIEF DESCRIPTION OF THE DRAWINGS

The following description of the preferred embodiments is merelyexemplary in nature and is in no way intended to limit the invention,its application, or uses. For purposes of clarity, the same or similarreference numbers are used in the drawings to identify similar elements.

FIG. 1 illustrates an exemplary implantable medical device system thathas leads;

FIG. 2 illustrates an exemplary torque wrench engaged with a setscrewlocated inside an implantable medical device;

FIG. 3 shows a schematic cutaway view of the header of FIG. 1 takenalong lines 3-3;

FIG. 4A is a schematic exterior view of an exemplary torque wrench;

FIG. 4B is a schematic side view of the exemplary torque wrench of FIG.4A such that the handle is cutaway along lines 4B-4B;

FIG. 5A is a schematic exterior view of the exemplary handle depicted inFIGS. 4A-4B;

FIG. 5B is a schematic interior view of an exemplary handle;

FIG. 5C is a schematic view of a triangular-shaped anti-rotation memberlocated on an inner diameter of another exemplary handle;

FIG. 5D is a schematic view a rectangular-shaped anti-rotation memberlocated on an inner diameter of yet another exemplary handle;

FIG. 5E is a schematic view of a half-circle shaped anti-rotation memberlocated on an inner diameter of yet another exemplary handle;

FIG. 5F is a schematic side view of the exemplary handle of FIG. 4A suchthat the handle is cutaway along lines 4B-4B;

FIG. 6A is a schematic view of an exemplary drive shaft member;

FIG. 6B shows a schematic side view of an exemplary drive shaft member;

FIG. 6C is a schematic view of an exemplary drive shaft tool interface;

FIG. 7 shows a schematic cutaway view of the torque wrench of FIG. 4Ataken along lines 7-7;

FIG. 8 shows a cutaway view of the torque wrench of FIG. 4A taken alonglines 7-7;

FIG. 9 shows a schematic view of the torque wrench of FIG. 4A such thatthe handle is cutaway along lines 7-7;

FIG. 10A depicts a top schematic view of an exemplary torque wrench inwhich the handle is rotated counterclockwise until flexible fingers forthe drive shaft member engage anti-rotation members in the handle;

FIG. 10B depicts a top schematic view of the exemplary torque wrenchdepicted in FIG. 10A in which the handle is rotated clockwise todisengage flexible fingers from the anti-rotation members in the handle;

FIG. 10C depicts a top schematic view of the exemplary torque wrenchdepicted in FIG. 10B in which the handle is again rotated clockwise sothat flexible fingers engage the anti-rotation members in the handle;

FIG. 10D depicts a top schematic view of the exemplary torque wrenchdepicted in FIG. 10C in which the handle is again rotated clockwise suchthat a breakaway torque is applied and flexible fingers begin to rotatepast the anti-rotation members in the handle;

FIG. 11 depicts a top schematic view of a flexible finger relative to aninner wall of the handle for the torque wrench;

FIG. 12A depicts a top schematic view of an exemplary torque wrench inwhich the handle is rotated counterclockwise to disengage flexiblefingers from the anti-rotation members in the handle;

FIG. 12B depicts a top schematic view of the exemplary torque wrenchdepicted in FIG. 12A in which the handle is again rotatedcounterclockwise such that a breakaway torque is applied and flexiblefingers begin to rotate past the anti-rotation members in the handle;

FIG. 13A depicts a top schematic view of an exemplary torque wrench inwhich the handle is rotated counterclockwise to disengage flexiblefingers from the anti-rotation members in the handle;

FIG. 13B depicts a top schematic view of the exemplary torque wrenchdepicted in FIG. 13A in which the handle is again rotatedcounterclockwise such that a breakaway torque is applied and flexiblefingers begin to rotate past the anti-rotation members in the handle;

FIG. 14 is a schematic exterior view of another exemplary torque wrench;

FIG. 15 depicts a cutaway view of the exemplary torque wrench from FIG.14 taken along lines 15-15;

FIG. 16 is a schematic side view of the exemplary handle of FIG. 14 inwhich the handle is cutaway along lines 15-15;

FIG. 17 is a schematic exterior view of another exemplary torque wrench;

FIG. 18 depicts a cutaway view of the exemplary torque wrench from FIG.17 taken along lines 18-18;

FIG. 19 is a schematic side view of the exemplary handle of FIG. 17 inwhich the handle is cutaway along lines 18-18;

FIG. 20 is a schematic exterior view of the drive shaft member from thetorque wrench depicted in FIG. 17;

FIG. 21 is a schematic exterior view of the torque wrench depicted inFIG. 17;

FIG. 22 depicts a cutaway view of the exemplary torque wrench from FIG.21 taken along lines 22-22;

FIG. 23 is a schematic exterior view of another exemplary torque wrench;

FIG. 24 depicts a cutaway view of the exemplary torque wrench from FIG.23 taken along lines 24-24;

FIG. 25 is a schematic side view of the exemplary handle of FIG. 23 inwhich the handle is cutaway along lines 24-24;

FIG. 26 is a schematic exterior view of the drive shaft member from thetorque wrench depicted in FIG. 23;

FIG. 27 is a schematic exterior view of another exemplary torque wrench;

FIG. 28 depicts a cutaway view of the exemplary torque wrench from FIG.27 taken along lines 28-28;

FIG. 29 is a schematic side view of the exemplary handle of FIG. 27 inwhich the handle is cutaway along lines 28-28;

FIG. 30 is a schematic exterior view of the drive shaft member from thetorque wrench depicted in FIG. 27; and

FIG. 31 is a schematic exterior view of an exemplary torque wrench;

FIG. 32A is a schematic side view of the exemplary torque wrench of FIG.31 in which a compression member is expanded around a drive shaftmember;

FIG. 32B is a schematic side view of the exemplary torque wrench of FIG.31 in which a compression member is compressed around the drive shaftmember;

FIG. 33 is a schematic exterior view of an exemplary handle;

FIG. 34 is a schematic side view of an exemplary drive shaft member;

FIG. 35 is a schematic side view of an exemplary drive shaft member;

FIG. 36 is a schematic side view of yet another exemplary torque wrench;

FIG. 37 is a schematic side view of an exemplary drive shaft member; and

FIG. 38 is a schematic side view of an exemplary drive shaft member.

DETAILED DESCRIPTION

The following description of the preferred embodiments is merelyexemplary in nature and is in no way intended to limit the invention,its application, or uses. For purposes of clarity, similar referencenumbers are used in the drawings to identify similar elements.

The present disclosure relates to a surgical torque wrench. A surgicaltorque wrench can be used to securely connect a medical electrical leadto an implantable medical device. One or more embodiments of the torquewrench consist solely of a first component and a second component. Byforming a torque wrench with two components instead of, for example,nine or more components as that which is used with conventional torquewrenches for IMDs, the torque wrench of the present disclosure is easierto manufacture, assemble and potentially use. Additionally, a lower costcan be realized by patients who undergo surgery using the torque wrenchdescribed herein.

In one or more embodiments, a surgical torque wrench includes a firstcomponent that has first and second ends and a bore extending betweenthe first and second ends. At the second end of the first component, aplurality of anti-rotation members extend from an inner surface of thebore. The second component includes a middle portion having a first andsecond ends. A drive shaft extends from the first end while a pluralityof fingers extend from an exterior surface of the second component. Thesecond component is received in the bore of the first component, suchthat the drive shaft partially extends outside the first end of thefirst component and the plurality of fingers are interdigitate with theanti-rotation members of the first component.

Referring to FIGS. 1-2, an implantable medical device (IMD) 20 caninclude implantable pacemakers, implantable cardioverter defibrillator(ICD) devices, cardiac resynchronization therapy defibrillator devices,neurostimulators, drug pumps or combinations thereof. Exemplary IMDs arecommercially available as including one generally known to those skilledin the art, such as the Medtronic CONCERTOT™, SENSIA™, VIRTUOSO™,RESTORE™, RESTORE ULTRA™, sold by Medtronic, Inc. of Minnesota. IMD 20can include an implantable case, housing or body assembly 22.Implantable case 22 can be formed of appropriate materials and includeappropriate features, such as a hermetically sealed body wall 24 a. Bodywall 24 a comprises substantially conductive material such as titanium.

Contained within or associated with case 22 can be a power device 25such as one or more batteries and/or capacitors encased in housing orcase body wall 24 b, a controller assembly 26, and a connector body 27.Controller assembly 26 can include a circuit board having a processor,memory, transmitter, receiver, and/or other appropriate portions.Connector body 27 can extend from or be integrated with case 22. At itsdistal end, connector body 27 or header can include one or more ports 28a,b that interconnects with one or more connector terminals 30 a,b ofone or more lead assemblies 32 a,b. Exemplary connector bodies 27 caninclude International Standard-1 (IS-1) connectors, IS-4 connectors orother suitable connectors contained within an insulative body.

Lead assemblies 32 a,b can comprise respective lead bodies 34 a,b. Leadbodies 34 a,b include one or more elongated insulated conductiveelements. Each conductive element extends from a proximal end 5 to adistal end 7. In particular, as shown in FIG. 3, a conductive elementfor the lead assemblies 32 a,b has a terminal pin 137 located at theproximal end 5 and, at the distal end 7, an uninsulated portion of aconductive element connects with one of the electrodes such as a ringelectrode or a tip electrode 36 a,b.

To connect a lead body 34 a,b to the IMD 20, the terminal pin 137, whichextends from lead body 34 a,b, is placed through a bore in connectorbody 27 and inside a setscrew block 160. Connector 200, such as a setscrew, is dielectrically insulated from body fluid outside the IMD 10through a silicone grommet 190. A torque wrench 100 contacts theconnector 200 by passing through a slit (not shown) in the grommet 190.An exemplary torque wrench 100 for applying an appropriate amount oftorque to connector 200 is depicted in FIGS. 4A-4B. Torque wrench 100can comprise, or consist of, a handle 170 and a drive shaft member 150which are used, in combination, to tighten connector 200 onto a terminalpin 137. The proximal end 224 of drive shaft 150 can include anintegrally formed drive shaft tool interface 220, which is configured toconnect with connector 200. The drive shaft member 150 is positionedwithin a bore of handle 170 and snaps into place once snap groove 250 ofdrive shaft member 150 connects with snap protrusion 255 of handle 170.Drive shaft member 150 includes a position member 240 that extendsthrough an aperture (not shown) of handle 170 and positions the driveshaft member 150 to rotate about rotational axis 237. Additionally,flexible fingers 230, which extend from the drive shaft member 150 andsubstantially protrude in a perpendicular direction relative to thedrive shaft axis 235, selectively engage with anti-rotation members 270(FIG. 5B) that extend from the handle 170. Referring briefly to FIG. 8,the torque wrench handle 170 can then rotate until its anti-rotationmembers 270 connect with the flexible fingers 230 on the drive shaftmember 150. Further rotation of handle 170 allows torque to be appliedto connector 200 until connector 200 is sufficiently tightened againstterminal pin 137, as depicted in FIG. 2. While connector 200 is shown asa setscrew, connector 200 can also be a nut, bolt or other suitablefastener.

FIGS. 5A-5E depict a handle 170. In one or more embodiments, handle 170can be a cylindrically-shaped body with an inner wall 174 that forms abore 176 extending from a distal end 175 (second end) to a proximal end177 (first end) and an exterior surface 184 configured to be heldbetween at least two fingers of a user's hand. The proximal end 177 isclosest to the drive shaft tool interface 220 whereas the distal end 175is farthest from the drive shaft tool interface 220.

A plurality of anti-rotation members 270 or protrusions are formed onthe inner wall 174 of handle 170 near or at the distal end 175. Forexample, anti-rotation members 270 can be located from about 0.05 inchesto about 1.5 inches from an edge 244 at the distal end 175. In otherembodiments, anti-rotation members 270 can be located from about 0.01inches to about 2.5 inches from an edge 244 at the distal end 175. Inother embodiments, anti-rotation members 270 can be located from about 0inches to about 5 inches from an edge 244 at the distal end 175.

As depicted in FIG. 5B, anti-rotation members 270 can include a surface274, flat surfaces 275 and a curved end 276. Surface 274, which can beflat, or, substantially flat, is directly contacted by a distal portion236 of fingers 230 of drive shaft member 150 while curved end 276provides sufficient rigidity to secure anti-rotation members 270 inposition. The distal portion 236 of fingers 230 can also contact flatsurfaces 275 and/or curved end 276.

Anti-rotation members 270, extending into bore 176, can be formed by avariety of shapes. For example, anti-rotation members 270 can possess ashape that is substantially elliptical, substantially cylindrical,substantially rectangular, substantially triangular or other suitableshapes. FIG. 5C depicts an anti-rotation member 270 with a substantiallytriangular cross-section. Substantially triangular can involve ananti-rotation member within 20 percent of a precise triangular shape.FIG. 5D depicts an anti-rotation member 270 with a substantiallyrectangular cross-section. FIG. 5E depicts an anti-rotation member 270with a substantially half-circle cross-section.

Handle 170 can further include a plurality of inner diameters in orderto receive and secure drive shaft member 150 within bore 202. Forexample, as shown in FIG. 5F, the plurality of inner diameters caninclude a first inner diameter 262 (ID1), a second inner diameter 264(ID2), a third inner diameter 266 (ID3), and a fourth inner diameter 245(ID4). Exemplary diameters are presented below in table 1; however,other sizes can also be used.

TABLE 1 Exemplary dimensions for a handle (dimensions in inches) ID1 ID2ID3 ID4 Embodiment 1 0.25 to 0.35 0.20 to 0.25 0.20 to 0.25 0.10 to 0.15Embodiment 2 0.15 to 0.50 0.10 to 0.50 0.10 to 0.50 0.05 to 0.50Embodiment 3 0.10 to 1   0.10 to 1   0.10 to 1   0.05 to 1   Embodiment4 0.01 to 4   0.01 to 4   0.01 to 4   0.01 to 4  

Referring to FIGS. 4A-5E, the exterior surface 184 of the handle 170 caninclude gripping elements. For example, FIG. 5B depicts protrusions 172such as convex protrusions in handle 170 can aid in gripping the handle170. Recessed regions or concave regions in handle 170 can also be usedto allow a user to better grip handle 170. The convex protrusions orrecessed regions can be elongated, short and/or small dots. Referringbriefly to FIG. 9, the outer diameter 186 a,b of the handle 170 can varyalong the handle's 170 rotational axis 237 to provide enhanced grippingfeatures. In some embodiments, outer diameter 186 a,b can range fromabout 0.3 inches to about 1.2 inches. In other embodiments, outerdiameter 186 a,b can range from about 0.1 inches to about 2.5 inches. Inyet other embodiments, outer diameter 186 a,b can range from about 0.05inches to about 3.5 inches.

Referring to FIGS. 6A-6C, drive shaft member 150 comprises a first end238 (the drive shaft end), a middle portion 152, and a second end 154.In one or more embodiments, first end 238, middle portion 152, andsecond end 154 are integrally formed together. First end 238 includes adrive shaft tool interface 220, a drive shaft 156, a snap groove 250,and drive shaft surface 260 a,b. Drive shaft 156 is preferablyintegrally formed to drive shaft member 150. In one embodiment, a rigidtool interface is formed by a drive shaft 156 material that can be morerigid than the material used for the rest of the drive shaft member 150.For example, the rigid tool interface can comprise a metal or alloywhile the rest of the drive shaft member 150 could be a polymer such asplastic. Exemplary polymers can include acrylonitrile butadiene styrene(ABS) polyetherimide (PEI) manufactured by SABIC Innovative Plasticslocated in Houston, Tex.) and polyaryletheretherketone PEEK commerciallyavailable from Solvay located in Houston, Tex.

In one embodiment, a metal drive shaft 156 is insert molded into aplastic body in which the drive shaft 156 and the plastic body togetherform the drive shaft member 150. In this embodiment and in otherembodiments, the flexible fingers 230 can be integrally formed as partof the drive shaft member 150 during the molding process.

Drive shaft tool interface 220, depicted in FIG. 6C, is integrally orseparately formed to drive shaft 156. Drive shaft tool interface 220 caninclude a distal side (not shown) located adjacent to drive shaft 156,and a proximal side 224 as shown in FIG. 4A. The proximal side 224directly touches or contacts the connector 200. Proximal side 224 oftorque wrench tool interface 220 is configured to securely attach to anopposing exterior surface of connector 200. Many torque wrench toolinterfaces 220 can be applied to one or more of the embodimentsdescribed herein. Tool interface 220 can be configured to connect with avariety of screw drives disposed on connector 200. Exemplary screw drivetypes can be slotted, Philips, hex, torx, spanner head, triple square orother suitable types.

Referring to FIG. 6B, drive shaft 156 comprises a longitudinal element158 integrally formed with a base portion 162 that can be flared.Longitudinal element 158 is typically solid and can possess a diameterthat ranges from about 0.01 inches to about 0.5 inches. In typicalembodiments, the longitudinal element 158 possesses a diameter thatranges from about 0.025 inches to about 0.2 inches. The length of thelongitudinal element 158 can range from about 0.01 inches to about 5inches. In typical embodiments, the length of the longitudinal element158 can range from about 0.1 inches to about 2 inches. Base portion 162is proximal to drive shaft bearing surfaces 260 a,b and snap groove 250.More particularly, base portion 162 is closer to the torque wrench toolinterface 220 than drive shaft bearing surfaces 260 a,b and snap groove250. Snap groove 250 can include an outer diameter that ranges fromabout 0.01 inches to about 4 inches. In typical embodiments, snap groove250 can include an outer diameter that ranges from about 0.2 inches toabout 1.5 inches.

Middle portion 152 comprises a body portion 153 with a variety of outerdiameters in order to support and securely connect to handle 170. Outerdiameters can include outer diameter one (OD1), outer diameter two(OD2), and outer diameter three (OD3) which can couple with ID1, ID2,and ID3, respectively of handle 170. The inner diameter 262, 264, 266,245 dimensions, that define the interior geometry of the handle 170, areat least slightly larger than the corresponding outer diameter OD1-OD4dimensions of the drive shaft member 150 such that the drive shaftmember 150 is able to spin freely relative to the handle 170 unless theflexible fingers 230 collide or contact the anti-rotation members 270.Spin freely occurs when a torque that is less than half of the breakawaytorque is able to cause the drive shaft member 150 to rotate relative tothe handle 170. Exemplary outer diameter dimensions for drive shaft 156are presented below in Table 2.

TABLE 2 Exemplary dimensions for a drive shaft (dimensions in inches)OD1 OD2 OD3 OD4 Embod- 0.24 to 0.34 0.19 to 0.24 0.19 to 0.24 0.09 to0.14 iment 1 Embod- 0.14 to 0.49 0.09 to 0.49 0.09 to 0.49 0.04 to 0.49iment 2 Embod- 0.09 to 0.99 0.09 to 0.99 0.09 to 0.99 0.04 to 0.99 iment3 Embod- 0.009 to 3.99  0.009 to 3.99  0.009 to 3.99  0.009 to 3.99 iment 4

The second end 154 includes a position member 240 (referred to as aposition cylinder) and a plurality of flexible fingers 230. Positionmember 240, shaped as a cylinder, is configured to extend through anaperture 242 so that position member 240 can rotate. The inner diameterof the position aperture 245 is slightly larger than the outer diameterof the position cylinder 240.

As shown, plurality of fingers 230 comprise at least four fingers 230,however, any number of fingers 230 can be used. For example, one or morefingers 230 can be used on the second end 154 of the drive shaft member150. In one or more embodiments, the plurality of fingers 230 aresymmetrically spaced apart from each other. In another embodiment,plurality of fingers 230 are asymmetrically spaced apart from eachother.

Referring to FIGS. 6A-6B, and 7-13, flexible fingers 230 are sized suchthat flexible fingers 230 typically are unable to touch any part of thehandle 170 except the anti-rotation members 270. The drive shaft member150 has a plurality of flexible fingers 230 extending from an exteriorsurface. While flexible fingers 230 can follow a tortuous path; in oneor more embodiments, fingers 230 protrude in a perpendicular orsubstantially perpendicular direction relative to the drive shaft axis235 such that the generally flat proximal portion of fingers 230typically point in a direction that is away from the drive shaft axis235. Substantially perpendicular includes perpendicular plus or minus 50degrees relative to drive shaft axis 235. In other embodiments, theflexible fingers extend from an exterior surface that is notsubstantially perpendicular.

Referring to FIGS. 6B and 11, each relaxed flexible finger 230 comprisesa first portion 232, a second portion 234, and a third portion 236, eachof which can be integrally formed as a single finger. In one or moreembodiments, the flexible fingers 230 attach to the first portion base155 of the drive shaft member 150. First portion 232 extends radiallyaway from the drive shaft axis 235 of drive shaft member 150. The driveshaft axis 235 runs through the middle of the drive shaft member 150from the first end 238 to the second end 154.

Second portion 234 is integrally formed to first and third portions 232,236, respectively. In one or more embodiments, second portion 234 can becurved. In some embodiments, the angle between the first portion 232 andthe second portion 234 ranges from 0 degrees to 120 degrees. In someembodiments, third portion 236 (also referred to as a distal portion,gripping portion or a coupling portion) is substantially perpendicularto first and/or third portions 232, 236, respectively. Second portion234 typically can move up to 90 degrees from a relaxed position to astressed position. In some embodiments, second portion 234 can move upto 150 degrees from a relaxed position to a stressed position. Intypical embodiments, each finger 230 a-d possesses the flexibility toelastically deform until the finger 230 touches the surface of the driveshaft member 150 from which the finger 230 extends and then spring backto about the finger's 230 relaxed position without breaking. The fingers230 do not include a helical spring like conventional torque wrenches.

Polymeric material can be used to form the flexible fingers 230 as wellas the remaining portions of drive shaft member 150. Typically, thepolymeric material selected for forming flexible fingers 230 providessufficient flexibility such that fingers 230 do not relax or creep overtime due to compressive forces imparted from the handle 170 on theflexible fingers 230 when the torque wrench 100 is not in use. Exemplarymaterial that can be used to form fingers 230 can include polyetherimide(PEI), although other polymeric material can be used such aspolyaryletheretherketone (PEEK), acrylonitrile butadiene styrene (ABS).Other suitable polymers can also be used. In one or more embodiments,the flexible finger 230 can bend toward the drive shaft axis 235 inorder to rotate or move past the anti-rotation member 270.

A fully assembled exemplary torque wrench 100 is depicted in FIGS. 4A-B.In one or more embodiments, the drive shaft member 150 and the handle170 are assembled by simply pushing the drive shaft member 150 into theproximal end 177 of opening or bore 176 located in the handle 170, whichis closest to the snap protrusion 255. Drive shaft member 150 can berotated or moved while being pushed into handle 170 so that theplurality of fingers 230 are positioned interdigitate with theanti-rotation members 270. Once the snap protrusion 255 of handle 170resides in the snap groove 250 and the position cylinder 240 resides inthe position aperture 242, the torque wrench 100 is fully assembled.

The small clearance or gap (not shown) between the drive shaft bearingsurfaces 260 and the handle bearing surfaces 265 and the small gap (notshown) or clearance between the position cylinder 240 and the positionaperture 242 ensures the drive shaft axis 235 is generally aligned withthe handle axis 237 even when the handle 170 rotates relative to thedrive shaft member 150. The assembler or user can then verify thathandle 170 is able to rotate relative to the drive shaft member 150. Thehandle axis 237 runs through the middle of the handle 170 from thedistal end 175 to a proximal end 177.

To rotate handle 170, torque is applied between the drive shaft member150 and the handle 170, which causes the flexible fingers 230 to contactthe anti-rotation members 270. If breakaway torque is applied, theflexible fingers 230 can elastically deform and bend sufficiently tomove past the anti-rotation members 270. Breakaway torque is a maximumlevel of torque that torque wrench 100 can apply between the handle 170and the drive shaft member 150. For example, a torque wrench 100 canhave a breakaway torque of 14 ounce-inches. In this case, a user couldapply any torque from 0 ounce-inches up to 14 ounce-inches. If the userapplied a torque less than 14 ounce-inches and the handle 170 wasengaged with the drive shaft member 150, the handle 170 would not rotatemore than 360 degrees relative to the drive shaft member 150. An appliedtorque that is equal to or greater than the breakaway torque can causeflexible fingers 230 to sufficiently bend and move past theanti-rotation members 270 such that the handle 170 can rotate more than360 degrees relative to the drive shaft member 150. If a user tried toapply a torque greater than 14 ounce-inches, the handle 170 would beginto rotate relative to the drive shaft member 150, thus limiting themaximum level of torque the user could apply to approximately 14ounce-inches. Once a user has applied the breakaway torque between thetorque wrench 100 and the connector 200 to tighten the connector 200onto the terminal pin 137, the lead 32 a is securely joined with theheader 140, as shown in FIG. 2.

FIGS. 10A-D depict rotation of the drive shaft member 150 within handle170. These figures also show the flexibility of each finger 230 a-d,each of which lack a helical spring. The drive shaft member 150 remainssubstantially stationary while handle 170 rotates, which causesplurality of fingers 230 a-d to move. For example, as shown in FIG. 10A,plurality of fingers 230 a-d, placed interdigitate with theanti-rotation members 270 a-d within the bore of the handle 170, arelocked against anti-rotation members 270 a-d. As handle 170 rotates, theposition of each finger 230 a-d moves relative to anti-rotation member270 a-d. A gap 280 exists between inner wall 178 of handle 170 and thirdportion 236 of each finger 230 as depicted in FIG. 11. While handle 170continues to be rotated counterclockwise, plurality of fingers 230 a-dengage anti-rotation members 270. In this position, anti-rotationmembers 270 prevent plurality of fingers 230 a-d from moving further inthe counterclockwise direction. Referring to FIG. 10B, handle 170 isthen rotated clockwise, which unlocks plurality of fingers 230 fromanti-rotation members 270.

FIG. 10C depicts handle 170 rotating slightly clockwise while the driveshaft member 150 remains stationary, which engages plurality of fingers230 a-d with anti-rotation members 270. Further clockwise rotation ofhandle 170, as shown in FIG. 10D, causes the plurality of fingers 230a-d to begin to rotate past anti-rotation members 270 as a breakawaytorque is applied to the handle 170 while the drive shaft member 150remains stationary. The breakaway torque can cause the plurality offingers 230 a-d to deform and move past anti-rotation members 270.

FIGS. 12A-13B depict additional finger 230 geometries that can beimplemented. For example, FIG. 12A shows fingers 230 in a relaxedposition. Each finger is depicted as being in a substantiallycylindrical shape. In this embodiment, fingers 230 are perpendicular orsubstantially perpendicular to drive shaft axis 235 of drive shaftmember 150. Rotating the handle 170 in the counterclockwise direction610A relative to the drive shaft member 150 with a torque that is atleast as large as the counterclockwise breakaway torque causes thefingers 230 to deform such that the fingers 230 can rotate past theanti-rotation members 270 as shown in FIG. 12B. In this embodiment, thefingers 230 flex up to about 90 degrees as the fingers 230 rotate pastthe anti-rotation members 270.

FIG. 13A shows yet another embodiment with fingers 230 in the relaxedposition. In this embodiment, the fingers 230 extend from the driveshaft member 150 at an angle compared to a direction perpendicular tothe drive shaft axis 235 yet the fingers 230 still extend in asubstantially perpendicular direction relative to the drive shaft member150. In some embodiments, the angle relative to a directionperpendicular to the drive shaft axis 235 at which the fingers 230extend from the drive shaft member 150 is between about 0 and 25degrees. In other embodiments, the angle is between about 0 and 45degrees. In still yet other embodiments, the angle is between 0 and 90degrees. Rotating the handle 170 in the counterclockwise direction 610Arelative to the drive shaft member 150 with a torque that is at least aslarge as the counterclockwise breakaway torque causes the fingers 230 todeform such that the fingers 230 can rotate past the anti-rotationmembers 270 as shown in FIG. 13B. In this embodiment, the fingers 230can flex from a relaxed position to a stressed position up to about 180degrees as the fingers 230 rotate past the anti-rotation members 270.

FIGS. 14-30 depict various exemplary torque wrench embodiments toillustrate the wide range of ways in which flexible fingers 230 can beused to create torque limiting mechanisms. Skilled artisans willrecognize the similarities between the depicted torque wrenchembodiments which share common trait(s) including the lack of a helicalspring to limit the torque transferred between the handle 170 and thedrive shaft member 150.

FIGS. 14-16 depict an exemplary torque wrench 300 with flexible fingers230 to limit the maximum torque that can be transferred between thehandle 170 and the drive shaft member 150. In this embodiment, theflexible fingers 230 extend from the handle 170 and substantially pointtowards the drive shaft axis 235 while a plurality of anti-rotationmembers 270 or protrusions are formed on the outer surface of the driveshaft member 150. FIG. 15 shows a cutaway view of the exemplary torquewrench 300 from FIG. 14 taken along lines 15-15. The anti-rotationmembers 270, previously described, can be positioned on the drive shaftmember 150 such that the anti-rotation members 270 are able to engage orcontact the fingers 230. While fingers 230 are depicted as being locatednear the distal end of the handle 170, skilled artisans appreciate thatfingers 230 can be located anywhere on interior portion of the handle170 that faces the drive shaft member 150. In another embodiment, thefingers 230 are located near the proximal end of the handle 170. In someembodiments, the fingers 230 are placed 0 to 0.5 inches from the distalend of the handle 170. In yet other embodiments, the fingers 230 areplaced anywhere from about 0 to about 1.5 inch from the distal end ofthe handle 170.

In one or more embodiments, the anti-rotation members 270 deform lessthan the fingers 230. In another embodiment, the anti-rotation members270 do not deform more than ten percent of the rotational deformation ofthe fingers 230. In yet another embodiment, the fingers 230 and theanti-rotation members 270 deform about equally.

The combined deformation of each connecting pair, which is one finger230 and one anti-rotation member 270 that are touching or engaged,should be sufficient to allow the handle 170 to rotate relative to thedrive shaft member 150 more than 360 degrees when a torque at least aslarge as the breakaway torque is applied between the handle 170 and thedrive shaft member 150. The combined deformation of each connecting pairshould not be sufficient to allow the handle 170 to rotate relative tothe drive shaft member 150 more than 360 degrees when a torque less thanthe breakaway torque is applied between the handle 170 and the driveshaft member 150. For example, a finger 230 might deform 70 degrees andan anti-rotation member 270 that is engaged with the finger 230 mightdeform 20 degrees. The deformation of the finger 230 without thedeformation of the anti-rotation member 270 may be insufficient to allowthe finger 230 to rotate past the anti-rotation member 270 when abreakaway torque is applied. Yet, the deformation of the finger 230combined with the deformation of the anti-rotation member 270 can besufficient to allow the finger 230 to rotate past the anti-rotationmember 270 when a breakaway torque is applied.

Deformation of the fingers 230 and/or the deformation of theanti-rotation members 270 due to an applied torque in at least onerotational direction should not damage the fingers 230 and/or theanti-rotation members 270. Damage may occur when the breakaway torque ina given rotational direction changes by more than 50 percent from onecycle to the next cycle. A cycle involves increasing the torque betweenthe handle 170 and the drive shaft member 150 until the handle 170 movesmore than 360 degrees but less than 720 degrees relative to the driveshaft member 150.

In one or more embodiments, applying the breakaway torque during onecycle in the clockwise direction typically does not change the breakawaytorque more than 50 percent in the next clockwise cycle, but exceedingthe breakaway torque in the counterclockwise direction will change thebreakaway torque more than 50 percent in the next cycle. For example, atorque wrench may not be damaged by clockwise cycles but can be damagedby counterclockwise cycles. In another example, a torque wrench may notbe damaged by counterclockwise cycles but can be damaged by clockwisecycles.

In one or more embodiments, fingers 230 are located near a cap 290disposed at the distal end of the torque wrench 100. Cap 290 simplifiesthe moldability of the rest of the handle 170 by allowing adequate moldtool access to the fingers 230. The torque wrench 300 in FIGS. 14-16 isassembled by first snapping or bonding the cap 290 onto distal end ofthe handle 170. Thereafter, the drive shaft member 150 is pressed intothe proximal end of the handle 170 until the snap protrusion 255 snapsinto the handle 170. FIG. 16 depicts a cutaway view of the handle 170from FIG. 14 taken along lines 15-15.

FIGS. 17-22 depict a torque wrench 400 in which the flexible fingers 230extend substantially parallel to the drive shaft axis 235. Moreparticularly, the flexible fingers 230 are attached to or extend fromthe handle 170. The fingers 230 are located near the proximal end of thehandle 170. In one or more embodiments, flexible fingers 230 can be usedto create a torque wrench that does not use a helical spring to limitthe torque transferred from the handle 170 to the drive shaft member150.

FIG. 18 shows a cutaway view of the exemplary torque wrench 100 fromFIG. 17 taken along lines 18-18. In this embodiment, a plurality ofanti-rotation members 270 or protrusions are formed on the outer surfaceof the drive shaft member 150. The anti-rotation members 270 arepositioned on the drive shaft member 150 such that the anti-rotationmembers 270 are able to engage or come in contact with the fingers 230.In this embodiment, fingers 230 are located on the handle 170 and extendparallel or substantially parallel to the drive shaft axis 235. Thefingers 230 can be located anywhere on an interior portion of the handle170 that faces the drive shaft member 150. In this embodiment, thefingers 230 are located near the proximal end of the handle 170. Inanother embodiment, the fingers 230 are located near the distal end ofthe handle 170.

In this embodiment, the anti-rotation members 270 deform less than thefingers 230. The interaction between the anti-rotation members 270 andthe fingers 230 prevent the handle from rotating more than 360 degreesrelative to the drive shaft member 150 unless a torque at least as largeas the breakaway torque is applied between the handle 170 and the driveshaft member 150. In this embodiment, applying the breakaway torque doesnot damage the fingers 230 and/or the anti-rotation members 270.

The torque wrench in FIGS. 17-20 is assembled by pressing the driveshaft member 150 into the proximal end of the handle 170 until the snapprotrusion 255 snaps into the handle 170. FIG. 19 depicts a cutaway viewof the handle 170 from FIG. 17 taken along lines 18-18. Fingers 230 inFIG. 19 also lack a helical spring. In some embodiments, the fingers 230and/or the anti-rotation members 270 comprise or consist of a polymericmaterial.

FIG. 22 shows a cutaway view of the exemplary torque wrench 400 fromFIG. 21 taken along lines 22-22. FIG. 22 depicts exemplary perpendicularlines 365 that are perpendicular to the drive shaft axis 235. Exemplarytorsional force direction 370, perpendicular to the exemplaryperpendicular lines 365, substantially acts on finger 230 m. Torsion isthe moment arm multiplied by the applied torsional force. In one or moreembodiments, a finger 230 that is substantially aligned with the driveshaft axis 235 deforms substantially along the torsional force direction370 plus or minus 45 degrees of the torsional force that acts on thefinger 230.

FIGS. 23-24 depict a torque wrench 500 in which the flexible fingers 230are attached to the drive shaft member 150 and the fingers 230substantially extend parallel to the drive shaft axis 235. FIG. 24 showsa cutaway view of the exemplary torque wrench 500 from FIG. 13 takenalong lines 24-24. In this embodiment, a plurality of anti-rotationmembers 270 or protrusions are formed on an interior surface of thehandle 170. FIG. 25 depicts the anti-rotation members 270 on theinterior surface of the handle. The anti-rotation members 270 arepositioned on the handle 170 such that the anti-rotation members 270 areable to engage or come in contact with the fingers 230, which in thisembodiment, are located on the drive shaft member 150 and extendsubstantially parallel to the drive shaft axis 235. The fingers 230 canbe located anywhere on the drive shaft member 150 that faces the handle170. In this embodiment, the fingers 230 are located on the drive shaftmember 150 near the proximal end of the handle 170.

In this embodiment, the anti-rotation members 270 do not deform. Thefingers 230 do not deform sufficiently to allow the drive shaft member150 to rotate relative to the handle 170 unless a torque at least aslarge as the breakaway torque is applied between the handle 170 and thedrive shaft member 150. FIG. 26 depicts the fingers 230 which are longand slender with rectangular surfaces. The fingers 230 and theanti-rotation members are not damaged when the breakaway torque isapplied between the handle 170 and the drive shaft member 150.

The torque wrench in FIGS. 23-26 can be assembled by pressing the driveshaft member 150 into the proximal end of the handle 170 until the snapprotrusion 255 snaps into the handle 170. The fingers 230 in FIG. 26lack a helical spring. In some embodiments, the fingers 230 and/or theanti-rotation members 270 comprise or consist of a polymeric material.In the torque wrench embodiment shown in FIGS. 23-26, the handle 170 isplastic and the drive shaft member 150 is metal. The drive shaft member150 in this embodiment can be formed by electrical discharge machining.A similar embodiment can be manufactured by stamping and forming thefingers 230 and then pressing the fingers 230 into a molded body whereinthe molded body and the fingers 230 comprise the drive shaft member 150.More specifically, a ring can be stamped or cut from a flat sheet ofmetal that is about approximately 0.035 inches thick. Next, the fingers230 can be manufactured by stamping or cutting multiple holes such asU-shaped holes into the metal sheet. The suspended metal sections formedby stamping or cutting multiple U-shaped holes are then bent or formedsuch that each suspended metal section extends at an angle of about 45to 90 degrees from the plane in which the majority of the metal ringresides. The suspended metal sections are fingers 230 and the ring isattached to the rest of the drive shaft member 150.

FIG. 27 depicts a torque wrench 600 in which the flexible fingers 230extend at an angle relative to the drive shaft axis 235. FIG. 28 shows acutaway view of the exemplary torque wrench 600 from FIG. 27 taken alonglines 28-28. In this embodiment, the fingers 235 are attached to thedrive shaft member 150 and the fingers 230 extend at an angle relativeto the drive shaft axis 235. In another embodiment, the fingers 230 areattached to the handle 170 and extend at an angle relative to the driveshaft axis 235.

FIG. 29 shows a cutaway view of the handle 170 from FIG. 27 taken alonglines 28-28. In this embodiment, a plurality of anti-rotation members270 or protrusions are formed on an interior surface of the handle 170.The anti-rotation members 270 are positioned on the handle 170 such thatthe anti-rotation members 270 are able to engage or come in contact withthe fingers 230, which in this embodiment, are located on the driveshaft member 150 and extend at an angle relative to the drive shaft axis235. FIG. 28 shows the finger extension angle 350, which depicts theangle at which the fingers 230 extend from the drive shaft member 150relative to the drive shaft axis 235 in this embodiment. The fingerextension angle can be 0 to 180 degrees from the drive shaft member 150relative to the drive shaft axis 235. The fingers 230 can be locatedanywhere on the drive shaft member 150 that faces the handle 170. Inthis embodiment, the fingers 230 are located on the drive shaft member150 near the middle of the handle 170. In another embodiment, thefingers 230 are located near the distal end of the drive shaft member150. In another embodiment, the fingers 230 are located near theproximal end of the drive shaft member 150.

The anti-rotation members 270 do not allow the fingers 230 to rotatepast the anti-rotation members 270 unless a torque at least as large asthe breakaway torque is applied between the handle 170 and the driveshaft member 150. When a torque at least as large as the breakawaytorque is applied between the handle 170 and the drive shaft member 150,the fingers 230 elastically deform to enable the fingers 230 to rotatepast the anti-rotation members 270. The deformation caused by thefingers 230 rotating past the anti-rotation members 270 does not damagethe fingers 230 and/or the anti-rotation members 270.

Torque wrench 600 in FIGS. 27-30 is assembled by pressing the driveshaft member 150 into the proximal end of the handle 170 until the snapprotrusion 255 snaps into the handle 170. The fingers 230 in FIG. 26lack a helical spring. In some embodiments, the fingers 230 and/or theanti-rotation members 270 consist of a polymeric material. In someembodiments, the fingers 230 and/or the anti-rotation members 270consist of a metal material. Metal fingers 230 can be formed byprocesses such as machining, stamping and forming or other suitablemethods.

FIG. 31 is a flow diagram that depicts formation of an exemplary torquewrench. At block 300, a first component is provided. The first componentcan be provided by being formed through introduction of one or morepolymers into a mold that undergoes a molding process. The firstcomponent can have a bore there through. For example, the firstcomponent can be a cylindrical body with a bore centrally locatedthrough the cylindrical body. Additionally, the first component can be ahandle or other suitable object. At block 320, a second component isprovided. The second component can be provided or formed throughintroduction of one or more polymers into a mold that undergoes amolding process. At block 330, the second component is coupled to thefirst component. The second component can include a middle portion thathas first and second ends. A drive shaft can extend from the first end.Additionally, a plurality of fingers extend from an exterior surface ofthe second end. The second component can be received in the bore of thefirst component, such that the drive shaft partially extends outside thefirst end of the first component and the plurality of fingersinterdigitate with the anti-rotation members of the first component. Thesecond component can be a drive shaft member or other suitable object.

Although the present disclosure has been described in considerabledetail with reference to certain disclosed embodiments, the disclosedembodiments are presented for purposes of illustration and notlimitation and other embodiments of the disclosure are possible. Forexample, in one or more other embodiments, torque wrench 100 is solelyformed of handle 170 and drive shaft member 150, as described herein. Itwill be appreciated that various changes, adaptations, and modificationsmay be made without departing from the spirit of the disclosure and thescope of the appended claims. In one or more embodiments, breakawaytorque in the clockwise direction can be different from the breakawaytorque in the counterclockwise direction due, at least in part, to theshape of the flexible fingers 230 and/or the shape of the anti-rotationmembers 270. In one or more embodiments, the flexible fingers 230 aresymmetrical in the clockwise direction and counterclockwise directionsuch that the breakaway torque in the clockwise direction is about equalto the breakaway torque in the counterclockwise direction. In anotherembodiment, the flexible fingers 230 are attached to or part of thehandle 170. In this embodiment, the flexible fingers generally extendtowards the drive shaft member 150 and the anti-rotation features arelocated on the drive shaft member 150. In yet another embodiment, theflexible fingers 230 are approximately aligned with the drive shaft axis235 and generally deform in a direction aligned with the direction ofthe torsion force rather than deform in a direction generallyperpendicular to the drive shaft axis 235. In some embodiments, thefingers 230 and/or the anti-rotation members 270 comprise or consist ofa polymeric material. Skilled artisans appreciate that the sizes ofcomponents can be modified to implement features of the embodiment(s)described herein.

FIGS. 31 through 35 depict yet another embodiment of a torque wrench800. Torque wrench 800 consists of, or, comprises a drive shaft member150, a handle 170, and a compressible member 310. In this embodiment,drive shaft member 150, depicted in FIGS. 34-35, includes a drive shaftend 158, a middle portion 152, finger end 154. Handle 170 is the same aspreviously described except, in this embodiment, handle 170 alsoincludes a bore area 312 which allows sufficient space to housecompressible member 310 between handle 170 and drive shaft member 150.Bore area 312 has an inner diameter that can range from about 0.2 inchesto about 0.4 inches. Bore area 312 can also extend in length along thedrive shaft axis from about 0.1 inches to about 0.25 inches. In anotherembodiment, the inner diameter for area 312 can be 0.1 inches to 0.5inches. In yet another embodiment, inner diameter for area 312 can be0.05 inches to about 0.70 inches. In still yet another embodiment, innerdiameter for area 312 can be 0.01 inches to about 1.5 inches.Additionally, area 312 can extend a distance of about 0.05 inches toabout 0.5 inches. In another embodiment, area 312 can extend a distanceof about 0.02 inches to about 1.5 inches.

In one or more embodiments, compressible member 310 surrounds a middleportion 152 of drive shaft member 150; however, compressible member 310can be placed in different locations along drive shaft member 150. Anexemplary compressible member 310 can include a spring, a wave washer, acantiever beam, or other suitable structures.

Compressible member 310, either free-standing or connected to handle 170and/or middle portion 152, is configured to move drive shaft member 150relative to handle 170 along drive shaft axis 235. The compressiblemember 310 is movable along the drive shaft member 150 between a firstconfiguration and a second configuration. A first configuration occurswhen the compressible member 310 is expanded or not compressed, asdepicted in FIG. 32A. In this configuration, torque wrench 800 is notbeing forced against a connector 200; therefore, the compressible member310 is in a relaxed or expanded position. An expanded position ofcompressible member 310 involves greater space between, for example,each filar of a coil as compared to a compressible member 310 that iscompressed. When torque wrench 800 is not engaged or pressed againstconnector 200, plurality of fingers 230 are disengaged fromanti-rotation members 270; therefore, handle 170 can spin freely orrelatively freely relative to drive shaft member 150.

A second configuration occurs when handle 170 is being forced against anobject. For example, a user can push the torque wrench 800 in thedirection of the tool interface 220 against a connector 200, as shown inFIG. 2. As the user continues to push the torque wrench 800 againstconnector 200, the compressible member 310 is compressed or shortenedalong drive shaft axis 235, as shown in FIG. 32B. Compressingcompressible member 800 locks or pushes together the handle 170 and thedrive shaft member 150 along the drive shaft axis 235. Specifically, atleast one or more fingers 230 are interlocked with anti-rotation members270. The handle 150 is then unable to spin freely and can transfersignificant torque to the drive shaft member 170. In this embodiment, nocoupling body is used between the handle 170 and the drive shaft member150. Instead, the flexible fingers 230 and the anti-rotation membersserve as the interlocking features between the handle 170 and driveshaft member 150.

FIGS. 36-38 depict yet another embodiment of a torque wrench 900. Torquewrench 900 consists of, or, comprises a drive shaft member 150 a, ahandle 170, and a compressible member 310. In this embodiment, handle170 includes protrusions 902 configured to mate with recessed areas 902in drive shaft member 150 a. In this embodiment, drive shaft member 150a is same as drive shaft member 150 except flexible members 230 a areshaped as cylindrical members instead of as flexible fingers 230.Compressible member 310 can then be slid over a middle portion of handle170 in order to move drive shaft member 150 a from a relaxed position toan engagement position. Torque wrench 900 operates in a manner similarto torque wrenches previously described herein.

Although the present disclosure has been described in considerabledetail with reference to certain disclosed embodiments, the disclosedembodiments are presented for purposes of illustration and notlimitation and other embodiments of the disclosure are possible

What is claimed is:
 1. An instrument comprising: a torque wrench for usewith an implantable medical device, the torque wrench comprising: ahandle having first and second ends and defining a bore extendingbetween the first and second ends, the handle including a plurality ofanti-rotation members extending from an inner surface into the bore atthe second end of the handle; a drive shaft member including a middleportion having a first and second ends, a drive shaft extending from thefirst end and a plurality of fingers extending from an exterior surfacethat is located inside the handle, the plurality of fingersinterdigitate with the anti-rotation members; and a compressible membersurrounding a middle portion of the drive shaft member, the compressiblemember being movable between a first configuration in which theplurality of fingers are disengaged from the anti-rotation members and asecond configuration in which the plurality of fingers are engaged tothe anti-rotation members for transferring torque to the drive shaft. 2.The instrument of claim 1, wherein the compressible member is coupledalong the radial axis of the middle portion of the drive shaft member.3. The instrument of claim 1, wherein the plurality of fingers extendsubstantially perpendicular to a drive shaft axis.
 4. The instrument ofclaim 1, wherein the drive shaft and the handle lack breakaway torque.5. The instrument of claim 1, wherein the drive shaft forms a snap fitconfiguration with the handle.
 6. The instrument of claim 2, wherein thecompressible member is one of a helical spring, and a wave washer. 7.The instrument of claim 2, wherein the compressible member engages theplurality of fingers to the anti-rotation members when the drive shaftlacks engagement to a connector.
 8. The instrument of claim 2, whereineach finger has a first portion, a second portion and a third portion.9. The instrument of claim 8, wherein the second portion is acurve-shaped portion relative to the first portion.
 10. The instrumentof claim 1, wherein the fingers consist of a polymeric material.
 11. Aninstrument comprising: a torque wrench for use with an implantablemedical device, the torque wrench comprising: a handle having first andsecond ends and defining a bore extending between the first and secondends, the handle including a plurality of anti-rotation membersextending from an inner surface into the bore at the second end of thehandle; a drive shaft member including a middle portion having a firstand second ends, a drive shaft extending from the first end and aplurality of fingers extending from an exterior surface that is locatedinside the handle, the plurality of fingers interdigitate with theanti-rotation members; and a compressible member surrounding a middleportion of the drive shaft member, the compressible member being movablebetween a first configuration in which the plurality of fingers aredisengaged from the anti-rotation members and a second configuration inwhich the plurality of fingers are engaged to the anti-rotation membersfor transferring torque to the drive shaft; wherein at least one fingerhas a first portion, a second portion and a third portion.
 12. Theinstrument of claim 11, wherein the second portion is a curve-shapedportion relative to the first portion.
 13. The instrument of claim 12,wherein the fingers consist of a polymeric material.
 14. The instrumentof claim 12, wherein an angle of less than 120° exists between the firstand second portions.
 15. The instrument of claim 12, wherein the secondportion can move up to 150° relative to the first portion.
 16. Theinstrument of claim 11, wherein the compressible member is one of ahelical spring, and a wave washer.